Endoscope

ABSTRACT

An endoscope configured to measure a specimen using a stripe image formed by projecting a light-dark pattern on the specimen, the endoscope including an insertion portion having an elongated shape; an imaging unit provided at a distal portion of the insertion portion and configured to acquire an image of the specimen; a lighting unit configured to illuminate an observation field of view of the imaging unit; and a pattern projector which emits projection light configured to project the light-dark pattern to the specimen and project the light-dark pattern on the specimen. The imaging unit includes an image sensor configured to image the image of the specimen; and an objective optical system configured to form the image of the specimen on the image sensor. The pattern projector includes a pattern generator configured to generate the light-dark pattern; and a projection optical system provided at the distal portion of the insertion portion and configured to emit the projection light to the specimen via the light-dark pattern. A radiation angle of the projection light in the projection optical system is smaller than an angle of view of the objective optical system. The objective optical system is in focus at farther point side than a minimum object distance which is a minimum value of an object distance at which the entire projected light-dark pattern enters an imaging field of view of the image sensor.

This application is a Continuation Application of U.S. Ser. No.14/078,223, filed Nov. 12, 2013, which is a Continuation Applicationbased on PCT Patent Application No. PCT/JP2012/063258, filed May 24,2012, whose priority is claimed from Japanese Patent Application No.2011-116140, filed May 24, 2011, the contents of all of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an endoscope, and more particularly, toan endoscope configured to project a pattern such as stripes or the likeon a specimen and measure a three-dimensional shape of a specimensurface.

Description of Related Art

In the related art, in order to inspect a specimen, an endoscopeincluding an imaging unit which has an optical system, an image sensor,and the like, and is arranged at a distal end of a long insertionportion of the endoscope is used. In such endoscopes, a constitution inwhich a plurality of stripe images formed by projecting a stripe patternon a specimen are acquired while offsetting a phase of the stripepattern, and a three-dimensional shape of the specimen is calculatedusing the plurality of stripe images is known. For example, US PatentPublication Application, Publication No. 2009/0225321 discloses anendoscope having two projection windows which are configured to projectstripes and are arranged at a distal surface of an insertion portion ofthe endoscope. The endoscope disclosed in US Patent PublicationApplication, Publication No. 2009/0225321 is configured such that thestripe pattern is displayed on the entire stripe image acquired by theimaging unit.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, an endoscopeconfigured to measure a specimen using a stripe image formed byprojecting a light and dark pattern on the specimen includes: aninsertion portion having an elongated shape; an imaging unit provided ata distal portion of the insertion portion and configured to acquire animage of the specimen; a lighting unit configured to illuminate anobservation field of view of the imaging unit; and a pattern projectorhaving a light source configured to emit projection light to project thelight and dark pattern on the specimen. The pattern projector generatesa region, in which the light and dark pattern is not projected, in atleast one end of a direction in which stripes of the light and darkpattern are arranged in an imaging field of view of the imaging unit, ina state in which the light and dark pattern is projected on thespecimen.

According to a second aspect of the present invention, in the endoscopeaccording to the first aspect, the imaging unit may include: an imagesensor configured to image the image of the specimen; and an objectiveoptical system configured to form the image of the specimen on the imagesensor. The pattern projector may include: a pattern generatorconfigured to generate the light and dark pattern; and a projectionoptical system provided at the distal portion of the insertion portionand configured to radiate the projection light from the light source tothe specimen via the light and dark pattern. A radiation angle of theprojection light in the projection optical system may be smaller than anangle of view of the objective optical system.

According to a third aspect of the present invention, in the endoscopeaccording to the first or second aspect, in the state in which theregion, in which the light and dark pattern is not projected, isgenerated in at least one end of the direction in which the stripes ofthe light and dark pattern are arranged in the imaging field of view ofthe imaging unit, the objective optical system may be in focus.

According to a fourth aspect of the present invention, in the endoscopeaccording to any one of the first to third aspects, only one projectionwindow configured to project the light and dark pattern on the specimenmay be provided at a distal surface of the insertion portion.

According to a fifth aspect of the present invention, the endoscopeaccording to any one of the first to fourth aspects may further includea display having a display screen configured to display the image of thespecimen. The display may display a frame on the display screen, theframe showing a predicted projection position on the display screen ofthe stripe pattern projected on the specimen.

According to a sixth aspect of the present invention, the endoscopeaccording to the fifth aspect may further include a controllerconfigured to perform measurement of a three-dimensional shape of thespecimen with respect to only a region disposed in the frame on theimage displayed on the display screen.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a constitution of an endoscopeaccording to an embodiment of the present invention.

FIG. 2 is a front view showing a distal surface of an insertion portionof the endoscope according to the embodiment of the present invention.

FIG. 3 is a schematic view showing a relation between an angle of viewof an objective optical system and a radiation angle by a projectionoptical system in the endoscope according to the embodiment of thepresent invention.

FIG. 4 is a schematic view showing an example of a pattern projectionimage displayed on a monitor of the endoscope according to theembodiment of the present invention.

FIG. 5A is a schematic view showing a frame displayed on the monitor ofthe endoscope according to the embodiment of the present invention.

FIG. 5B is a schematic view showing the frame displayed on the monitorof the endoscope according to the embodiment of the present invention.

FIG. 6 is a schematic view showing a relation between an angle of viewof an objective optical system and a radiation angle by a projectionoptical system in a modified example of the endoscope according to theembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an endoscope and a measurement method according to anembodiment of the present invention are described.

First, a constitution of an endoscope 1 according to the embodiment isdescribed. FIG. 1 is a block diagram showing the constitution of theendoscope 1. FIG. 2 is a front view showing a distal surface of aninsertion portion 10 of the endoscope 1.

The endoscope 1 is a measurement endoscope configured to measure aspecimen using a pattern projection image formed by projecting a lightand dark pattern on the specimen. In addition, the endoscope 1 is usedfor internal observation of the specimen, observation of the specimendisposed at a position that a conventional observation device cannoteasily access, or the like.

As shown in FIG. 1, the endoscope 1 includes the insertion portion 10having an elongated shape, and a main body portion 20 to which a distalend of the insertion portion 10 is connected.

The insertion portion 10 is formed in a tubular shape. The insertionportion 10 is inserted into the inside of the specimen or an access pathto the specimen. The insertion portion 10 is provided with an imagingunit 30, a lighting unit 40, and a pattern projector 50. The imagingunit 30 acquires the image of the specimen. The lighting unit 40illuminates an observation field of view in front of the insertionportion 10. The pattern projector 50 projects the light and dark patternon the specimen. In the embodiment, the pattern projector 50 projectsthe stripe pattern, as a light and dark pattern, on the specimen.

As shown in FIG. 2, an opening 11, a lighting window 12, and aprojection window 13 are provided at a distal surface 10 a of theinsertion unit 10. The opening 11 allows external light to enter anobjective optical system 32 of the imaging unit 30. The lighting window12 radiates illumination light from the lighting unit 40 to a forwardside of the insertion portion 10. The projection window 13 radiates astripe pattern from the pattern projector 50 to the forward side of theinsertion portion 10.

The imaging unit 30 includes an imager 31, the objective optical system32 and an imager controller (a controller) 33. The imager 31 is disposedin the vicinity of a distal end of the insertion portion 10. Theobjective optical system 32 is disposed in front of the imager 31. Theimager controller 33 is connected to the imager 31.

An area image sensor having, for example, a rectangular sensor region inwhich square-shaped pixels are arranged in a lattice shape andconfigured to image an image by detecting a light quantity that entersthe sensor region at every pixel can be employed as the imager 31. Inthe embodiment, in the image imaged by the imager 31, a short side ofthe sensor region of the imager 31 is represented as a vertical side. Inaddition, a long side of the sensor region of the imager 31 isrepresented as a horizontal side. As a specific example of the imager31, various known constitutions including various kinds of image sensorssuch as CCD, CMOS, and so on, may be appropriately selected and used.

The objective optical system 32 is disposed in the opening 11 of theinsertion portion 10. The objective optical system 32 has apredetermined angle of view (view angle). The objective optical system32 allows the reflected light in the observation field of view definedby the angle of view to enter the imager 31, and forms the image of thespecimen. In addition, the objective optical system 32 has a covermember 32 a having optical transparency. The cover member 32 a seals theopening 11.

The imager controller 33 is provided in the main body portion 20. Inaddition, the imager controller 33 is connected to the imager 31 by awiring 34 extending in the insertion portion 10. The imager controller33 performs various kinds of controls such as driving of the imager 31,setting of acquiring a video signal, and so on.

The lighting unit 40 includes a first light source 41, a lightingoptical system 42, a first fiber bundle 43, and a first incident opticalsystem 44. The first fiber bundle 43 guides light of the first lightsource 41 to the lighting optical system 42. The first incident opticalsystem 44 is disposed between the first light source 41 and the firstfiber bundle 43.

The first light source 41 is a light source configured to emit whitelight. The first light source 41 is disposed in the main body portion20. A known light source such as a halogen or mercury lamp, or the like,may be appropriately selected and employed as the first light source 41.In the embodiment, the halogen lamp is employed as the first lightsource 41. The light emitted from the first light source 41 isillumination light used to illuminate the specimen.

The lighting optical system 42 is attached to the distal end of theinsertion portion 10 or the vicinity of the distal end. The lightingoptical system 42 has a cover member 42 a having optical transparency,and a group of lenses (not shown). The cover member 42 a is provided inthe lighting window 12 of the insertion portion 10. The lighting opticalsystem 42 spreads the light radiated from the first light source 41 to arange of a field of view appropriate for an angle of view of theobjective optical system 32 and emits the light from the lighting window12, illuminating all of the observation field of view.

The first fiber bundle 43 extends from the vicinity of the lightingoptical system 42 to the vicinity of the first light source 41 in themain body portion 20 through the insertion portion 10. The kind of thefirst fiber bundle 43 is not particularly limited, and a conventionallight guide may be used.

The first incident optical system 44 collects the light emitted from thefirst light source 41 to substantially the same diameter as that of thefirst fiber bundle 43 and efficiently guides the light into the firstfiber bundle 43.

The pattern projector 50 includes a second light source 51, a projectionoptical system 52, a second fiber bundle 53, a second incident opticalsystem 54, and a pattern generator 55. The second fiber bundle 53 guidesthe light of the second light source 51 to the projection optical system52. The second incident optical system 54 is disposed between the secondlight source 51 and the second fiber bundle 53. The pattern generator 55is disposed on an optical path of the light emitted from the secondlight source 51.

The second light source 51 is a light source configured to emitdifferent light from the first light source 41. The second light source51 is disposed in the main body portion 20. An LED light source, a laserlight source, or the like, may be employed as the second light source51. In the embodiment, the LED light source is employed as the secondlight source 51. The light emitted from the second light source 51 isprojection light used to project a stripe pattern.

The projection optical system 52 is attached to the distal end of theinsertion portion 10 or the vicinity of the distal end. The projectionoptical system 52 has a cover member 52 a having optical transparency.The cover member 52 a is provided in the projection window 13 of theinsertion portion 10. As shown in FIG. 2, the projection window 13 isdisposed at a position adjacent to a short side of the imager 31 whenseen from a side of the distal surface 10 a of the insertion portion 10.

In addition, the cover member 52 a provided at the projection window 13may have a lens shape. The projection optical system 52 projects thelight radiated from the second light source 51 into the observationfield of view from the one projection window 13 at a predeterminedradiation angle corresponding to the angle of view of the objectiveoptical system 32.

Here, a relation between the angle of view of the objective opticalsystem 32 and the radiation angle of the projection light by theprojection optical system 52 in the embodiment is described.

FIG. 3 is a schematic view showing the relation between the angle ofview of the objective optical system 32 and the radiation angle of theprojection optical system 52. In FIG. 3, reference character Orepresents a position of the objective optical system 32. Further,reference character P represents a position of the projection opticalsystem 52.

As shown in FIG. 3, in the embodiment, an angle of view θv of theobjective optical system 32 is spread to equal angles using a depthdirection of the objective optical system 32 (a direction of an objectdistance) as a centerline (shown by reference character A1 in FIG. 3).In addition, a radiation angle θp of the projection optical system 52 isspread to equal angles about a centerline A2 parallel to a centerlineA1. Further, the angle of view θv of the objective optical system 32 andthe radiation angle θp of the projection optical system 52 satisfyθv>θp.

In addition, provided that a depth of a near point side of the objectiveoptical system 32 is represented by Ln and a depth of a far point sidethereof is represented by Lf, the shortest object distance L1 at whichthe entire projected stripe enters the field of view satisfies Ln≥L1.

According to the above-mentioned relation, when the object distance isin focus (within a depth from Ln to Lf), the entire stripe pattern isdisposed in the angle of view of the objective optical system 32.

In addition, in the embodiment, a distance d between a center of theobjective optical system 32 and a center of the projection opticalsystem 52 is set to be smaller than a depth L1, which is a minimum valueof the measurable object distance. For this reason, the distance d issufficiently smaller than the object distance Ln. For this reason,within a range in which the imaging unit 30 is in focus, a position ofthe stripe taken in the image is not largely varied.

As shown in FIG. 1, the second fiber bundle 53 extends from the vicinityof the projection optical system 52 to the vicinity of the second lightsource 51 in the main body portion 20 through the insertion portion 10.Like the first fiber bundle 43, a general light guide may be used as thesecond fiber bundle 53.

The second incident optical system 54 collects the light emitted fromthe second light source 51 to substantially the same diameter as that ofthe second fiber bundle 53 and efficiently guides the light into thesecond fiber bundle 53.

The pattern generator 55 is configured to be capable of forming thestripe pattern. For example, a slit plate having a plurality of slits,or a transparent plate, on which a stripe pattern is drawn, formed ofglass, resin, or the like, may be used as the pattern generator 55. Thestripe pattern is preferably a strip-shaped stripe pattern in whichbrightness of the stripes is smoothly and periodically varied. Inaddition, the stripe pattern may be a stripe pattern in which a white orblack color has a rectangular shape and brightness thereof is varied.

The stripe pattern in the embodiment is a pattern extending in ashort-side direction of the sensor region of the imager 31 and disposedin parallel in a long-side direction of the sensor region of the imager31 at a predetermined interval (see FIG. 2). That is, in the embodiment,the stripe pattern extends in a vertical direction of the image acquiredby the imaging unit 30 when the stripe pattern is projected on a planefacing the distal end of the insertion portion. In addition, here, thestripe pattern is taken as lines disposed in parallel in a horizontaldirection (see FIG. 4).

Moreover, a liquid crystal shutter module configured to be capable ofswitching transmission and non-transmission of the light at everydevice, a microelectromechanical system (MEMS) mirror module including afine reflective mirror at every device, or the like may be used as thepattern generator 55. In this case, since each device is individuallycontrolled and the stripe pattern having an appropriate phase can beformed without moving the entire pattern generator 55, the constitutionof the pattern projector 50 can be simplified. Switching of the stripepattern is performed by a pattern controller (a controller) 56 connectedto the pattern generator 55.

FIG. 4 is a schematic view showing an example of a stripe patternprojected on the specimen.

As shown in FIG. 3, as the angle of view θv of the objective opticalsystem 32 and the radiation angle θp of the projection optical system 52have the above-mentioned relation, as shown in FIG. 4, the patternprojector 50 projects a stripe pattern 100 on the specimen. In thisstate, non-projection regions X in which the stripe pattern is notprojected (a right non-projection region X1 and a left non-projectionregion X2) are formed at both ends in a direction in which the stripesof the stripe pattern are arranged in the imaging field of view of theimaging unit 30.

In addition, the relation between the angle of view of the objectiveoptical system 32 and the radiation angle of the projection light in theprojection optical system 52 may satisfy θp≥θv. In this case, while thestripe pattern is not entirely disposed in the angle of view of theobjective optical system 32, the non-projection region X (the rightnon-projection region X1 or the left non-projection region X2) in whichthe stripe pattern is not projected is formed at one of both directionsin which the stripes of the stripe pattern are arranged in the imagingfield of view.

The above-mentioned imager controller 33, a light source controller (acontroller) 21, and a main controller (a controller) 22 are provided inthe main body portion 20. The light source controller 21 controls anoperation of emitting the illumination light from the lighting unit 40and an operation of emitting the projection light from the patternprojector 50.

A video processor 27 and the main controller 22 are connected to theimager controller 33. The video processor 27 processes a video signalacquired by the imager 31. The main controller 22 controls an operationof the imager controller 33. The video processor 27 and the maincontroller 22 are provided in the main body portion 20.

A monitor (a display) 28 is connected to the video processor 27. Themonitor 28 displays the video signal processed by the video processor 27as the image. The video processor 27 generates an image, which is aframe F showing a predicted projection position on the display screen ofthe stripe pattern projected on the specimen, and outputs the image tothe monitor 28 to overlap the image acquired by the imaging unit 30.

Since the distance d shown in FIG. 3 is substantially smaller than theobject distance Ln or the object distance Lf, the position of the stripepattern displayed on the monitor 28 is moved leftward and rightwardwithin a certain level of range without a large variation. That is, theposition of the stripe pattern slightly moves on the image displayed onthe monitor 28 in the horizontal direction according to the objectdistance with respect to the specimen.

FIGS. 5A and 5B are schematic views showing the frame F displayed on themonitor of the endoscope 1. As shown in FIGS. 5A and 5B, in theembodiment, even when the stripe pattern 100 is maximally moved in thehorizontal direction, the position of the frame F is set to surround aregion on which the stripe pattern 100 is displayed. Accordingly, thestripe pattern 100 is disposed in the frame F regardless of an actualposition of the stripe pattern 100 in the image displayed on the monitor28. When the position of the frame F is set as described above, there isno need to adjust the position of the frame F in accordance with theposition of the stripe pattern 100. For this reason, processing ofdisplaying the frame F is simplified.

The monitor 28 displays the image of the specimen and the frame Fshowing the predicted projection position of the stripe pattern on thedisplay screen. In addition, the measurement result of thethree-dimensional shape or various kinds of information detected in useof the endoscope 1 are displayed on the monitor 28.

As shown in FIG. 1, the light source controller 21 is connected to thefirst light source 41, the second light source 51, and the maincontroller 22. The light source controller 21 controls ON/OFF of thefirst light source 41 and the second light source 51 based on thecontrol by the main controller 22.

The main controller 22 is further connected to an operating unit 23, aRAM 24, a ROM 26, an auxiliary storage device 25, and the patterncontroller 56.

The operating unit 23 has switches configured to allow a user to performvarious kinds of inputs to the endoscope 1, and so on.

In addition, a touch panel provided to overlap the display screen of themonitor 28 may be employed as the operating unit 23.

The RAM 24 functions as a work area used upon imaging of the specimenusing the endoscope 1, measurement of the three-dimensional shape of thespecimen using the endoscope 1, or the like.

For example, firmware or the like is recorded on the ROM 26. The ROM 26is configured such that the firmware or the like is read upon startingof the endoscope 1.

The auxiliary storage device 25 may employ, for example, a storagedevice or a magnetic storage device having a non-volatile memory whichis rewritable.

The main controller 22 sets the region on the image surrounded by theframe F generated by the video processor 27 to a target region T (seeFIG. 3) used for measuring the three-dimensional shape, and obtains thethree-dimensional shape of the specimen with respect to the inside ofthe target region T only.

As a measurement method for measuring the three-dimensional shape of thespecimen by the main controller 22, a method of obtaining a phase of thestripe pattern by a phase shift method, a Fourier transform method, orthe like, and calculating the three-dimensional shape of the specimenbased on the phase of the stripe pattern may be used.

An operation of the endoscope having the above-mentioned constitution isdescribed.

In use of the endoscope 1, first, a user inserts the insertion portion10 shown in FIG. 1 into the inside of the specimen, the access path tothe specimen such as the conduit line or the like, or the like, andmoves the distal end of the insertion portion 10 forward to apredetermined observation area. The user performs inspection or the likeof the specimen by switching an observation mode for observing apredetermined area of the specimen and a measurement mode for measuringa three-dimensional shape of the observation area as needed.

In the observation mode, the light source controller 21 that receives anorder of the main controller 22 shown in FIG. 1 turns the first lightsource 41 on and turns the second light source 51 off. As a result, thewhite light is radiated from the lighting unit 40 to the observationfield of view while the stripe pattern is not projected from the patternprojector 50, and the observation field of view is illuminated(hereinafter, this illumination state is referred to as an “observationstate”). The image of the illuminated specimen is imaged by the imager31 through the objective optical system 32. The video signal transmittedfrom the imager 31 is processed by the video processor 27 and displayedon the monitor 28. The user can observe the specimen by the image of thespecimen displayed on the monitor 28 and save the image as needed.

When the observation mode is switched to the measurement mode, the userinputs an order of switching the mode. When the user performs the inputof switching from the observation mode to the measurement mode, acontrol signal for displaying the image of the frame F on the monitor 28is output from the main controller 22 to the video processor 27.Accordingly, the image of the frame F corresponding to the predictedprojection position of the stripe pattern is displayed on the monitor 28(see FIGS. 5A and 5B).

In addition, in this state, the stripe pattern 100 is still notprojected, and the user can observe the image of the specimenilluminated by the illumination light.

The user adjusts the position of the insertion portion 10 or the likesuch that an area of the specimen that requires measurement of thethree-dimensional shape enters the frame F on the monitor 28. In a statein which the required area is disposed in the frame F displayed on themonitor 28, the user starts the measurement of the three-dimensionalshape using the switch or the like (not shown) of the operating unit 23.

When the measurement of the three-dimensional shape is started, first,at least one image is acquired by the imaging unit 30 in a state inwhich the illumination light from the lighting unit 40 shown in FIG. 1is radiated. Next, radiation of the illumination light from the firstlight source 41 of the lighting unit 40 is stopped by the light sourcecontroller 21, and radiation of the projection light from the secondlight source 51 of the pattern projector 50 is started by the lightsource controller 21.

When the projection light is radiated, the projection light passesthrough the pattern generator 55 and the projection optical system 52,and the stripe pattern is projected on the specimen.

As shown in FIG. 3, when the stripe pattern is projected on an object,the stripe pattern is projected on a portion in the angle of view of theobjective optical system 32, and the non-projection regions X in whichthe stripe pattern is not projected are generated at both ends in adirection in which the stripes of the stripe pattern are arranged inparallel in the imaging field of view of the imaging unit 30.

In addition, the positions of the stripe patterns in the angle of viewof the objective optical system 32 are different in accordance with theobject distance. However, in the embodiment, since the distance dbetween the center of the objective optical system 32 and the center ofthe projection optical system 52 is set to be sufficiently smaller thana measurable object distance, the position at which the stripe isdisplayed on the screen is not varied largely. For this reason, evenwhen the position of the stripe pattern is moved, the position of thestripe pattern is configured to be kept within substantially the frameF, which is previously set (see FIGS. 5A and 5B).

In a state in which the stripe pattern is projected on the specimen, theimaging unit 30 acquires the image of the specimen.

The image of the specimen on which the stripe pattern is projected isoutput to the main controller 22 via the video processor 27 shown inFIG. 1 as the stripe image. In addition, the image of the specimen istemporarily stored in the RAM 24 or the like.

Next, the phase of the stripe pattern is obtained from one patternprojection image acquired by the imaging unit 30 through theabove-mentioned phase shift method, the Fourier transform method, or thelike, by the main controller 22.

In addition, when the measurement of the three-dimensional shape isperformed using a temporal phase shift method, a plurality of patternprojection images having different phases are imaged by the imaging unit30, and the phase of the stripe pattern photographed in the plurality ofpattern projection images is obtained by the main controller 22. In theendoscope 1 according to the embodiment, the non-projection region X inwhich the stripe pattern is not projected is generated in at least aportion of each of the plurality of imaged pattern projection images.For this reason, correspondence between the stripe photographed on thepattern projection image and the stripe of the projected stripe patternis relatively easily performed using a boundary between the region onwhich the stripe pattern is projected and the non-projection region X asa starting point. Accordingly, three-dimensional coordinates in a realspace can be calculated from the obtained phase. Next, when the targetregion T which becomes a target in which the three-dimensional shape ofthe specimen is measured (i.e., a measurable range of the field of view)is set to a region inside the frame F, as distribution of thethree-dimensional coordinates in the target region T is obtained, thethree-dimensional shape of the specimen can be obtained. In addition,calculation of measuring the three-dimensional shape of the specimen isnot limited in the target region T but may be performed within a rangein which the light and dark pattern is photographed.

The result calculated by the main controller 22 is output to the videoprocessor 27 to be displayed on the monitor 28 as a numerical value oran image. In addition, the calculated result is received into theauxiliary storage device 25 as a file.

As the calculated result is displayed on the monitor 28, the user canrecognize the three-dimensional shape of the specimen in the frame F.

As described above, according to the endoscope 1 according to theembodiment, as the non-projection regions X in which the stripe patternis not projected are generated in both ends or one ends in a directionin which the stripes of the stripe pattern are arranged in the imagingfield of view of the imaging unit 30, it is possible to easily match thestripes photographed in the pattern projection image to the stripesprojected on the specimen. Accordingly, the object distance of thespecimen can be obtained by measurement of the pattern projection image.

While a method of forming two openings in which the projection opticalsystem 52 is disposed and projecting the stripe patterns from twodirections is known as another method of easily matching the stripepattern photographed on the pattern projection image to the stripepattern projected on the specimen, in the embodiment, since it is onlynecessary to form only one opening in which the projection opticalsystem 52 is disposed in the distal portion of the insertion portion 10,the insertion portion 10 can be further reduced in diameter.Alternatively, while a method of measuring the three-dimensional shapeof the specimen simultaneously using sensors configured to separatelymeasure the stripe pattern projected on the specimen and the objectdistance of the specimen is known, in the embodiment, since there is noneed to mount the sensor configured to separately measure the objectdistance of the specimen, the insertion portion 10 can be furtherreduced in diameter.

In addition, when the specimen is in focus, since the non-projectionregion X should be generated on the pattern projection image, the useronly focuses the specimen and starts the measurement of thethree-dimensional shape, and the operation of the endoscope 1 becomesconvenient.

Further, since the non-projection region is generated in both ends orone end in the direction in which the stripes of the stripe pattern arearranged in the imaging field of view of the imaging unit, it isrelatively easy to match the stripe pattern photographed on the patternprojection image to the projected stripe pattern. For this reason,misrecognition upon analysis of the stripe pattern can be reduced. Inaddition, deterioration of reliability of the measurement value ormeasurement performance can be prevented.

Further, since the frame F showing the predicted projection position ofthe stripe pattern projected on the specimen is displayed on the displayscreen of the monitor 28 by the main controller 22 and the videoprocessor 27, in use of the endoscope 1, the region in which thethree-dimensional shape can be measured can be recognized by the user.

In addition, since the stripe pattern is projected into substantiallythe frame F even when the position of the stripe pattern is varied inaccordance with the object distance, there is no need to actuallyproject the stripe pattern to recognize the region in which thethree-dimensional shape can be measured, and the measurement operationby the endoscope can be simplified.

Further, when the main controller 22 measures the three-dimensionalshape with respect to only the target region T using the inside of theframe F as the target region T, a calculation amount can be reduced morethan when the stripe pattern is photographed on the entire image and thethree-dimensional shape is calculated at the entire region of the image.In addition, in this case, the calculation result of thethree-dimensional shape can be rapidly obtained.

Further, since the radiation angle of the projection light is smallerthan the angle of view of the objective optical system 32, theprojection window 13 can be reduced in size in comparison with the casein which the radiation angle of the projection light is larger than theangle of view of the objective optical system 32. For this reason, theinsertion portion 10 can be further reduced in diameter.

(Modified Example 1)

Next, a modified example of the endoscope 1 described in theabove-mentioned embodiment is described.

FIG. 6 is a schematic view showing a relation between the angle of viewθv of the objective optical system 32 and the radiation angle θp of theprojection optical system 52 in the modified example.

In FIG. 6, reference character α and reference character β representradiation angles of the projection light by the projection opticalsystem 52. Specifically, reference character α represents a leftradiation angle with respect to a depth direction of the objectiveoptical system 32. Reference character β represents a right radiationangle with respect to the depth direction of the objective opticalsystem 32. The other reference characters shown in FIG. 6 are the sameas described in the above-mentioned embodiment.

As shown in FIG. 6, a magnitude of the radiation angle θp of theprojection light by the projection optical system 52 is a sum of theleft radiation angle α and the right radiation angle β. The modifiedexample has a different constitution from the above-mentioned embodimentin that the radiation angle θp of the projection light does not haveequal left and right angles with respect to a centerline in the depthdirection.

In the modified example, when the object distance in which all theprojected stripes enter the angle of view of the objective opticalsystem 32 is within a range from L1 to L2, Ln≥L1 and Lf≤L2 aresatisfied, and further, when the object distance is within the depth (arange from Ln to Lf), all the stripes can be photographed in the fieldof view.

In addition, here, the angle of view θv of the objective optical system32 and the radiation angle θp of the stripe projection satisfy arelation of θv>θp.

Even when the angle of view θv of the objective optical system 32 andthe radiation angle θp of the projection light have the above-mentionedrelation, like the above-mentioned embodiment, the non-projection regionX in which the stripe pattern is not projected can be generated at oneend in the direction in which the stripes of the stripe pattern arearranged in the imaging field of view of the imaging unit 30.

(Modified Example 2)

Next, another modified example of the endoscope 1 described in theabove-mentioned embodiment is described.

In the modified example, the video processor 27 configured to generatethe image of the frame F further includes a unit configured to adjustthe position of the frame F.

In the method of setting the frame F in the endoscope 1 according to theabove-mentioned embodiment, the stripe pattern may be actually displayedeven in the region outside the frame F. As a unit configured to vary theposition of the frame F in accordance with the projection position ofthe actual stripe pattern is further provided, the region in which thethree-dimensional shape can be measured can be more accurately seen bythe user.

Specifically, the unit configured to adjust the shape of the frame Frapidly detects both of left and right ends of the plurality of stripesin the stripe pattern and displays the frame F in accordance with acontour of the stripe pattern. Here, constant projection of the stripepattern interferes with observation of the specimen. For this reason,for example, the projection of the stripe pattern is performed only fora short time within a range that does not interfere with theobservation, for example, projection of the stripe pattern on thespecimen only for 1/30 of a second. As a method of rapidly detectingboth of left and right ends of the stripe, the image of the specimen isacquired in a state in which the stripe pattern is projected, and edgedetection of the stripe from the acquired image is performed.

The edge detection may be limited to a portion such as only one line ofa central portion of the image, or only a predetermined plurality oflines. Accordingly, a calculation amount for the edge detection can bereduced.

In addition, when a calculation speed for the edge detection can besubstantially obtained, in order to more accurately display the frame F,the frame F may be displayed from the edge detection result in all thelines on the image.

Further, the display of the frame F is updated at a predeterminedinterval, for example, every second. Since the projection itself of thestripe pattern is performed for a short time not to interfere withradiation of the illumination light to the specimen and observation ofthe specimen, the frame F can be displayed on the monitor 28 insubstantially real time without interference with observation of theobject on the screen.

As described above, in the modified example, the shape of the frame F isset based on the stripe pattern actually projected on the specimen. Forthis reason, in comparison with the case in which the frame F is set bythe method described in the above-mentioned embodiment, the region inwhich the three-dimensional shape can be measured can be seen by theuser exactly.

In addition, since the display of the frame F is updated at apredetermined interval, the region in which the stripe pattern isactually projected can be updated to the latest state at a predeterminedinterval. For this reason, the probability of not projecting the stripepattern in the frame F can be reduced.

While the above-mentioned embodiment has been described using theexample in which the opening in which the objective optical system isdisposed, the opening in which the lighting optical system is disposed,and the opening in which the projection optical system is disposed areformed one by one, each of these openings may be formed by two or more.

In addition, while the above-mentioned embodiment shows the example inwhich the projector configured to project the stripes extending in thevertical direction of the image imaged by the imaging unit is arrangedwith respect to the objective optical system in the horizontaldirection, the projector configured to project the stripes extending inthe horizontal direction of the image imaged by the imaging unit may bearranged with respect to the objective optical system in the verticaldirection. Alternatively, a shape of the light and dark pattern may be alattice-shaped pattern in which pluralities of vertical bands andhorizontal bands cross each other, or a plurality of points arranged invertical and horizontal directions at equal intervals, rather than theband-shaped stripes.

In addition, while the above-mentioned embodiment shows the example inwhich the first light source configured to radiate the illuminationlight and the second light source configured to radiate the projectionlight are disposed in the main body portion, the first light source andthe second light source may be provided at the distal end of theinsertion portion.

Further, the first light source and the second light source may includea shutter, a mirror module, or the like, configured to switch aradiation state of the light. In this case, a light source in whichlighting on/off is time-consuming can also be used as an appropriatelight source.

Furthermore, the shape of the frame may be set as an appropriate shapesuch as a round shape, a rectangular shape, and other polygonal shapes,in addition to the shape shown in the above-mentioned embodiment.

In addition, while the above-mentioned embodiment exemplarily shows theconstitution in which the non-projection regions are generated at bothends in the direction in which the stripes of the stripe pattern arearranged in the imaging field of view of the imaging unit, aconstitution in which the non-projection region is generated at one endin the direction in which the stripes of the stripe pattern are arrangedin the imaging field of view of the imaging unit may be provided. Whenthe non-projection region is generated at the one end in the directionin which the stripes of the stripe pattern are arranged in the imagingfield of view of the imaging unit, the boundary between thenon-projection region and the stripe pattern can be detected by the edgedetection or the like. In addition, in this case, it is possible tomatch the stripes of the projected stripe pattern to the stripes on theimage using the boundary between the non-projection region and thestripe pattern as a starting point.

Further, instead of the stripe pattern generator described in theabove-mentioned embodiment, a generator configured to generate a patternsuch as a lattice shape, a dotted shape, or the like, may be provided.

Hereinabove, while preferred embodiment of the present invention hasbeen described, the present invention is not limited to the embodiment.Additions, omissions, substitutions, and other modifications can be madeto the present invention without departing from the spirit and scope ofthe present invention. The present invention is not limited to theabove-mentioned description, and is only limited by the appended claims.

What is claimed is:
 1. An endoscope configured to measure a specimenusing a stripe image formed by projecting a light-dark pattern on thespecimen, the endoscope comprising: an insertion portion having anelongated shape; an imaging unit provided at a distal portion of theinsertion portion and configured to acquire an image of the specimen; alighting unit configured to illuminate an observation field of view ofthe imaging unit; and a pattern projector which emits projection lightconfigured to project the light-dark pattern to the specimen and projectthe light-dark pattern on the specimen, wherein the imaging unitincludes: an image sensor configured to image the image of the specimen;and an objective optical system configured to form the image of thespecimen on the image sensor, wherein the pattern projector includes: apattern generator configured to generate the light-dark pattern; and aprojection optical system provided at the distal portion of theinsertion portion and configured to emit the projection light to thespecimen via the light-dark pattern, wherein a radiation angle of theprojection light in the projection optical system is smaller than anangle of view of the objective optical system, and wherein the objectiveoptical system is in focus at a farther point side than a minimum objectdistance which is a minimum value of an object distance at which theentire projected light-dark pattern enters an imaging field of view ofthe image sensor.
 2. The endoscope according to claim 1, wherein adistance between a center of the objective optical system and a centerof the projection optical system is smaller than the minimum objectdistance.
 3. The endoscope according to claim 1, wherein the patternprojector produces a region in which the light-dark pattern is notprojected and which is on at least one side of the imaging field of viewof the imaging unit relative to a direction in which stripes of thelight-dark pattern are arranged, in a state in which the light-darkpattern is projected on the specimen.
 4. The endoscope according toclaim 3, wherein when a magnitude of the radiation angle of theprojection light is a sum of a left radiation angle and the leftradiation angle, the left radiation angle and the right radiation angleare different, the left radiation angle being a left radiation anglewith respect to a centerline in a depth direction of the objectiveoptical system, and the right radiation angle being a right radiationangle with respect to the centerline.
 5. The endoscope according toclaim 3, further comprising a display which has a display screenconfigured to display the image of the specimen and displays a frame onthe display screen, the frame showing a predicted projection position onthe display screen of the stripe pattern projected on the specimen. 6.The endoscope according to claim 5, wherein the display displays theframe on the display screen even when the light-dark pattern is notprojected on the specimen.
 7. The endoscope according to claim 6,further comprising a controller configured to switch an observation modefor observing the specimen and a measurement mode for measuring thespecimen, wherein the display configured to display the frame on thedisplay screen when the controller switches to the measurement mode fromthe observation mode.
 8. The endoscope according to claim 5, furthercomprising a video processor configured to generate an image of theframe, overlap the image of the frame onto the image of the specimenacquired by the imaging unit, and output the overlapped image to thedisplay.
 9. The endoscope according to claim 8, wherein the videoprocessor overlaps the image of the frame onto the image of the specimeneven when the light-dark pattern is not projected on the specimen. 10.The endoscope according to claim 9, further comprising a controllerconfigured to switch an observation mode for observing the specimen anda measurement mode for measuring the specimen, wherein the videoprocessor overlaps the image of the frame onto the image of the specimenwhen the controller switches to the measurement mode from theobservation mode.
 11. The endoscope according to claim 5, furthercomprising a controller configured to measure the specimen using onlythe image of specimen displayed within the frame.